When a postcard is used to notify personal and other information, an information concealing label is attached onto the postcard to conceal the personal information displayed on the postcard. Japanese Patent Laid-Open No. 6-332381 describes an example of such an information concealing label.
The information concealing label includes a label base formed of a paper or plastic film and an adhesive layer provided on the back side of the label base, and hence can be attached onto a postcard. Ink is printed on an inner portion of the adhesive layer surface but not on the periphery thereof. The portion of the adhesive layer that has ink printed thereon has a reduced adhesive strength, whereas the portion of the adhesive layer that has no ink printed thereon maintains an inherent adhesive strength. The adhesive layer therefore includes two kinds of adhesive portions: a strong adhesive portion positioned at the periphery and a weak adhesive portion positioned inside the periphery.
Further, the label base has perforations formed along the boundary between the weak adhesive portion and the strong adhesive portion described above, the perforations formed of short slits arranged linearly and intermittently. The label base can be cut along the perforations and the cut portion can be lifted.
The information concealing label is used in the following manner:
Information is first written in a predetermined information writing section printed on a postcard or any other card, and the information concealing label is overlaid and affixed onto the information writing section. The information written in the information writing section is thus concealed by the information concealing label. The strong adhesive portion positioned at the periphery of the back side of the information concealing label securely adheres to the postcard. Therefore, the information concealing label will neither peel off nor be peeled off even when one attempts to peel off the information concealing label itself, for example, during transportation of the mail because the strong adhesive portion positioned at the periphery has a strong adhesive strength; accordingly, no one can steal a glance at the information written in the information writing section. To look at the information written in the information writing section, the inner portion of the information concealing label must be removed by cutting through the perforations formed in the information concealing label and peeling off the weak adhesive portion. Therefore, in case that a malicious person has stolen a glance at the information during transportation of the mail, the perforations have been broken and a sign of such an action is left. A recipient can then notice that the information may have been leaked. Intact perforations in the received postcard ensure that information has not been leaked.
However, since the cuttable portion of the information concealing label of related art is formed of perforations linearly formed along the boundary, the cut surfaces of the perforations will not be fluffed but neatly aligned. Further, the weak adhesive portion of the adhesive layer can adhere again to the postcard even after peeled off the postcard. Therefore, a person other than a recipient can cut through the perforations and steal a glance at written information, and then reattach the weak adhesive portion of the information concealing label and neatly restore the cut perforations to original position. In this case, a recipient unlikely notices that the postcard has been opened.